There currently exists a significant aftermarket for devices which fasten to the underside of a vehicle hood. These devices include hood protectors, wind deflectors, headlight covers and bug screens. In most cases, these devices are fastened to the vehicle by drilling a hole through the vehicle body and inserting a sheet metal screw or similar fastener through the device and into the hole drilled in the vehicle body. The part of the vehicle body which is typically drilled is the underside of the vehicle hood. The precise locations of the drilled holes depend on the device to be attached and the configuration of the particular vehicle involved.
Some vehicles are manufactured with preexisting holes in interior spaces, for example in the engine compartment or in the vehicle's hood. In some cases, these holes can be used to attach devices to the vehicle by placing a block with a threaded bore on one side of the hole and then placing a screw through the device to be attached, through the hole and then through the threaded bore on the block. A similar effect can be achieved by clipping threaded plates onto or around protruding flat surfaces inside the engine compartment or on the underside of the vehicle's hood.
Drilling is very undesirable in the vehicle accessories aftermarket because it upsets the corrosionresistant coatings of the vehicle and irreversibly changes the vehicle's body panels. In addition, special tools are required to drill holes in a vehicle's body, and these may not always be available to the installer. Threaded clips and blocks eliminate the need to drill holes in the vehicle, however, they can be used only where the vehicle's existing bodywork allows, and they are typically less secure than the drilled holes.